Protein tyrosine phosphatase alpha (PTPα) knockout mice show deficits in Morris water maze learning, decreased locomotor activity, and decreases in anxiety

Receptor PTPα is a widely expressed transmembrane enzyme enriched in brain. PTPα knockout (PTPα^-/-) mice are viable and display no gross abnormalities. Brain and embryo derived fibroblast src and fyn activity is reduced to <50% in PTPα^-/- mice. These protein kinases are implicated in multiple aspects of neuronal development and function. However, the effect of the loss of function of the PTPα gene on behavior has yet to be investigated. PTPα^-/- and WT mice were tested for anxiety, swimming ability, spatial learning, cued learning, locomotor activity, and novel object recognition (NOR). PTPα^-/- mice were indistinguishable from WT in swimming ability, cued learning and novel object recognition. Knockout mice showed decreased anxiety without an increase in head dips and stretch-attend movements. During Morris water maze (MWM) learning, PTPα^-/- mice had increased latencies to reach the goal compared to WT on acquisition, but no memory deficit on probe trials. On reversal learning, knockout mice showed no significant effects. PTPα ^-/- mice showed decreased exploratory locomotor activity, but responded normally to a challenge dose of D-methamphetamine. The data suggest that PTPα serves a regulatory function in learning and other forms of neuroplasticity.